Fix retransmission timeout calculation.

[utcp] / utcp.c

diff --git a/utcp.c b/utcp.c
index ac162fe708a0d657abffb4cb62ecd4881a7fc79a..802d95a2ba87ea3de46d9235176f5273361e6ca7 100644 (file)
--- a/utcp.c
+++ b/utcp.c
@@ -415,13 +415,13 @@ static void update_rtt(struct utcp_connection *c, uint32_t rtt) {
        if(!utcp->srtt) {
                utcp->srtt = rtt;
                utcp->rttvar = rtt / 2;
-               utcp->rto = rtt + max(2 * rtt, CLOCK_GRANULARITY);
        } else {
                utcp->rttvar = (utcp->rttvar * 3 + absdiff(utcp->srtt, rtt)) / 4;
                utcp->srtt = (utcp->srtt * 7 + rtt) / 8;
-               utcp->rto = utcp->srtt + max(utcp->rttvar, CLOCK_GRANULARITY);
        }
 
+       utcp->rto = utcp->srtt + max(4 * utcp->rttvar, CLOCK_GRANULARITY);
+
        if(utcp->rto > MAX_RTO) {
                utcp->rto = MAX_RTO;
        }
@@ -1055,6 +1055,7 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
                                c->flags = UTCP_TCP;
                        }
 
+synack:
                        // Return SYN+ACK, go to SYN_RECEIVED state
                        c->snd.wnd = hdr.wnd;
                        c->rcv.irs = hdr.seq;
@@ -1410,6 +1411,9 @@ skip_ack:
                        break;
 
                case SYN_RECEIVED:
+                       // This is a retransmit of a SYN, send back the SYNACK.
+                       goto synack;
+
                case ESTABLISHED:
                case FIN_WAIT_1:
                case FIN_WAIT_2: